Exploratory Engineering and Solar Sailing

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The ‘Science’ section in today’s New York Times included an article about a space project that’s been a long time coming. Accompanied by the gorgeous graphic above, reporter Kenneth Chang describes how The Planetary Society, a not-for-profit advocacy group for space exploration, was planning to launch some small spacecraft, starting in May 2015, and test drive a solar sail.

A solar sail is an elegant idea. Light from the sun carries not just energy but momentum. This gentle but constant force, if captured by a sufficiently large sail, can propel a spacecraft until it is traveling hundreds of thousands of miles an hour. The concept of a solar sail is also an old one. Russian space visionary Konstantin Tsiolkovskii described the basic idea well before 1930. It was first picked up in the United States by science fiction writers. Then, a few weeks after the Soviets launched Sputnik I in October 1957, wunderkind physicist Richard L. Garwin added the rigor of numbers and equations.1

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Opening of Garwin’s 1958 paper; submitted for review in Nov. 1957.

It is an evocative idea – a ship, its sails “filled” by sunlight, wending its way through the solar system. Clipper ships of space…a nice blend of the past and the future. The poster below was for the 1978 Japanese film Message from Space, described by as Japan’s big-budget answer to Star Wars; notice the weird-looking craft in the upper right… (note: I’d love to hear from anyone who has seen this…the trailer is here. I’m amazed George Lucas didn’t sue.)

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Poster for Message from Space (1978)


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Anyway — as Garwin’s 1958 article notes, “the principle involved is simply to make use of the pressure of the sun’s light on a sail” in order to propel a craft.2

This diagram, from this article, explains why and how:

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But, while the principle might be simple, developing a suitable sail and the means to deploy it isn’t. So,despite the solar sail’s hypothetical potential for moving a spacecraft about the solar system, however, rockets remained the prevailing technology for space exploration during the Apollo era.

The idea of a solar sail-powered craft picked up speed again in the 1970s. In mid-1976, as NASA recovered from its post-Apollo hangover, Bruce C. Murray, the new head of the Jet Propulsion Laboratory in Pasadena, proposed several new missions that he believed had “good technical content and popular appeal.” One idea Murray suggested was a rendezvous with Halley’s Comet, scheduled to return to the inner solar system in 1986, with a craft powered by a solar sail. If successful, the propulsion method could perhaps be adapted for other NASA missions.3

The idea of solar sailing a spaceship to meet up with Halley’s Comet captured the public’s interest. As opposed to dirty, noisy rockets, with their obvious connections to ballistic missiles, solar sails appeared as a “soft technology” akin to solar and wind energy. But, in the end, high inflation and budget deficits scuttled the entire mission and no American craft flew to intercept Halley.4  A small group of persistent NASA engineers, however, started the World Space Foundation to pursue their goal of building and testing a solar sail prototype using funds from private sources and efforts to find a gentler alternative to rockets continued into the 1980s. Solar sails became one of the projects that The Planetary Society – started in 1980 by Murray, Carl Sagan, and Louis Friedman – explored.

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Friedman and prototype, shown in image from 1981 Science News article by Jonathan Eberhart.

The revived interest in solar sails caught my attention because it reminded me of some early R&D done by engineer K. Eric Drexler. In my book The Visioneers, I describe how Drexler interest in the technological future started with a passion for space-based settlements and manufacturing in the style of Gerard O’Neill. As Whole Earth Catalog publisher Stewart Brand described him, by 1977, Drexler was already“old Space Colony hand,” a true believer who once predicted that he “probably won’t die on this planet.” In time, Drexler shifted his focus to promote what he initially called “molecular engineering” i.e. a nascent form of nanotechnology.

The path to nanotechnology did not appear suddenly, however. After he finished his undergraduate degree at MIT in 1977, Drexler remained to do a master’s thesis in the Department of Aeronautics and Astronautics. For his research topic, the young engineer decided to design a “high performance solar sail system.” This, in fact, became the title of his 1979 M.S. thesis.

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Drexler imagined this technology could be prove essential for future space exploration efforts. Funded by a graduate fellowship from the National Science Foundation, Drexler investigated what the best materials would be for a solar sail and designed a machine, compact enough to fit inside NASA’s space shuttle, for fabricating ultra-thin sheets of metal films in space. Drexler’s visioneering also included a system to rig these pieces into a solar sail a few kilometers in diameter and a method for maneuvering the craft. To make the basic proof of concept more robust, Drexler even fabricated some small pieces of metal films in an MIT lab. Drexler dubbed his design concept “Lightsail,” to make it clear that it would be propelled by photons, not the solar wind or some adaptation of solar power cells. Drexler thought the research he did at MIT was innovative enough to warrant filing for a patent in 1980:

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And, of course, he promoted his ideas for solar sailing to fellow pro-space enthusiasts, particularly those in the L5 Society. An article he wrote for the February issue of Smithsonian brought the idea to an even wider audience.

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Drexler eventually began using the term “exploratory engineering,” an expression that well describes his approach to designing solar sails. Unlike the conventional engineering, which aims to build specific things and looks to a relatively short-term horizon, exploratory engineering for Drexler meant “designing things that we can’t yet build.” Today’s NYT article drove home the point that now we can build them.

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With the launch of The Planetary Society’s LightSail craft – perhaps the name owes a debt to Drexler – planned for this coming May, decades worth of dreaming and exploratory engineering will finally get a test-flight in space.

  1. Richard L. Garwin, “Solar Sailing: A Practical Method of Propulsion within the Solar System,” Jet Propulsion, 1958, 28, 188-89; also, Colin McInnes. “On the Crest of a Sunbeam.” New Scientist, January 5 1991: 31-33. []
  2. The day this article appeared, I received a nice email from Richard Garwin. He noted that his paper on solar sailing had actually been submitted to the IBM Journal of Research and Development in November 1956, a full year before it went to Jet Propulsion. So, Garwin was even more ahead of the curve than I originally noted. []
  3. My colleague Peter J. Westwick has an excellent telling of this history in his prizewinning book Into the Black: JPL and the American Space Program, 1976-2004 []
  4. European and Soviet missions, however, did successfully study the comet in 1986; John M. Logsdon, “Missing Halley’s Comet: The Politics of Big Science,” Isis, 1989, 80, 2: 254-80. []

The Once & Future Nano King*

K. Eric Drexler is back…and with a new set of bold ideas about the technological future, all detailed in his new book, Radical Abundance

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Drexler, shown in 2013, reading from his new book.

But there’s a twist! The man once christened by magazines like The Economist as the “father” of nanotechnology is imagining possible tomorrows made better without the n-word. More on this semantic shift below. But first – whatever happened to him in the first place?

Drexler’s story resembles those of once-prominent Communist Party members who fell into disfavor, vanished for a period and then, after some political rehabilitation, emerged back on the public stage.

In brief – Drexler first became interested in what he initially called “molecular engineering” in the late 1970s. A 1981 paper published in the Proceedings of the National Academy of Sciences laid out his general plan for “molecular manipulation.” (The word “nanotechnology” appeared nowhere in the manuscript. In fact, it would still be a few more years before Drexler began using the nano-word in talks and papers.) This was based, he predicted, on the design on de novo protein-based machines which would be able to move and position other molecules so as to build up structures and devices atom-by-atom. A 1986 book called Engines of Creation popularized Drexler’s ideas and the concept of nanotechnology to a wide audience. Tech enthusiasts, business leaders, mainstream scientists, and policy makers took note.

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Drexler’s 1986 book and various translations.

In Engines and other writings, Drexler took pains to describe his work not as scientific research but as “exploratory engineering” – designing things today that obey the laws of physics, chemistry, etc. yet which we can’t build yet. Konstantin Tsiolkovskii and other early space (as well as computer) pioneers worked in a similar fashion.

When it came to nanotechnology, Drexler literally defined it with his entry in Encyclopedia Brittanica’s Yearbook of Science and the Future 1990. Throughout much of the 1990s, when journalists and the general public considered nanotechnology, it was shot through of Drexlerian ideas (the nanobot meme, something Drexler himself eschewed, is a classic example of how some of his own imaginings were co-opted and adopted by others). Given the emerging differences between Drexler’s supporters and those in the mainstream research community who found his ideas too fanciful – a rift which widened into a chasm over the next decade – one senses that Drexler’s visioneering was succeeding perhaps too well. In the late 1990s and into the early 21st century, mainstream scientists gradually marginalized Drexler (my book The Visioneers describes all of this in great detail) and his ideas.

So, in 2003, when former president George W. Bush signed the 21st Century Nanotechnology Research and Development Act, there were a number of people standing behind him in the Oval Office. We see a Silicon Valley venture capitalist, a nano-business advocate, a Republican senator, a Nobel prize winning scientist. But Drexler was nowhere in sight.

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Where’s Drexler?

And the bill Bush signed bore scant resemblance to the type of nanotechnology Drexler had long promoted. In fact, by the time the National Nanotechnology Initiative was proceeding full-bore, Drexler was “the name that can’t be spoken in polite society,” or at least among many mainstream scientists and policy makers.1

But that is changing. Since 2011, Drexler has been in residence at the University of Oxford. He is currently listed as an “Academic Visitor” in the Oxford Martin Programme on the Impacts of Future Technology. (A video of him giving an address there is here…it’s worth watching if you have the time.) Drexler’s move to the U.K. is part of this rehabilitation. What could be more Establishment than Oxford? It also fits his overall career pattern of finding affiliations with elite schools (MIT, Stanford) while avoiding the traditional professorial career path. Drexler also has been giving more public talks and writing pieces for the mainstream press such as essays for The Guardian. Accompanying this are appearances at venues like TEDx, signs that Drexler is placing himself back in the role as a technology intellectual and public figure.

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Drexler at a 2013 TEDx event in Lisbon

But the signature event of Drexler’s rehabilitation back into public life (if not into the mainstream of scientific or engineering research) is the 2013 publication of his new book. In the same spirit as EnginesRadical Abundance is aimed at a popular audience. It’s much different from his highly technical 1992 tome Nanosystems, for example.

I’ll be saying more about the book itself in a later post. But without giving too much away, Radical Abundance is Drexler’s pivot away from nanotechnology. In his telling, that word has become much too politicized (thanks, in no small part, to his own writings) and vaguely applied. I mean, what exactly IS nanotechnology anyway? Is it passive nanoscale particles? Active nanoscale devices? A novel approach to building new materials? Or a massive government-run program? Well, it’s all of these and more. I tend to agree with Richard Jones’ interpretation and see nanotechnology more as a sociological phenomenon, a way of organizing and bridging research across disparate scientific fields. (The same can be said for the Obama administration’s current attempts to fashion a neuroscience initiative around brain mapping.)2

So, in Radical Abundance, Drexler has done away with nanotechnology and replaced it with — wait for it — “atomically precise manufacturing” (APM). This means two things in his telling – “manufacturing using machinery based on nanoscale devices” and “products built with atomic precision.”3 Drexler’s new term is, well, much more precise.

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A computer simulation of a nanoscale planetary gear. (Illustration: K. Eric Drexler/Nanorex Inc).

It’s about building things, not researching, for instance, the toxicological effects on nanoparticles on fish. And “manufacturing” connotes industry which suggests jobs. This is a good strategy. But, at its core, APM harkens back to his earlier program of building things atom by atom. APM invokes a world in which mechanical engineering combines with chemistry. And, just as in Engines, Radical Abundance offers plenty of examples of how APM offers promise and peril if adopted (which Drexler sees as pretty much inevitable).

I’m looking forward to reading Radical Abundance more closely. I’m very intrigued by the first skim I’ve made, especially those sections in which Drexler offers his view of the history of nanotechnology (and his removal from “official” narratives of same). The demarcation Drexler is trying to make between nanotechnology (old, confused) and “atomically precise manufacturing” (new, specific) is fascinating just as are Drexler’s borders between science and engineering.

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Mick in 1978…a long way from Exile on Mainstreet.

But what intrigues me most is the larger process of rehabilitation that I see taking place. We see attempts to do this quite frequently on the part of celebrities, musicians, and politicians. Sometimes this is done to craft a new public image (like the Rolling Stones going disco) or to try to atone for past sins (Newt Gingrich, ad infinitum). How common is this among scientists or technologists?

Sometimes such attempts at reinvention work. But many times – often? –  those attempting such feats end up singing the same songs and sinning as before.

* The joke here – probably not a good one – is that Drexler was also once part of a commercial venture called NanoRex.


  1. 2006 remark by physicist Richard A.L. Jones, quoted in Arie Rip and Marloes Van Ameron, “Emerging De Facto Agendas Surrounding Nanotechnology: Two Cases Full of Contingencies, Lock-Outs, and Lock-Ins,” in Governing Future Technologies, edited by Mario Kaiser, et al.  (New York: Springer, 2010), 131-55. []
  2. A recent article in Nature about the BRAIN initiative described recent efforts as “a large-scale sociological experiment, as the sprawling neuroscience community struggles to coalesce around a common research plan under intense public scrutiny and tough financial constraints.” []
  3. Radical Abundance, x. []